Power amplifier nonlinearities have a significant impact on the overall performance of modern digital communication systems.
The variation of the power amplifier gain with temperature plays an important role amongst power amplifier non-idealities. In order to ease the requirements placed on the rest of the transmit-chain blocks, such variation should be kept as small as possible. Baseband digital schemes exist to sense and counteract such variations, but their efficacy and viability depends on minimizing the gain variation in the analogue domain in the first place.
A further non-linearity is the AM-PM (amplitude modulation to phase modulation) non-ideal transfer characteristic. A great deal of effort is invested in complex baseband/digital pre-distortion schemes to sense and counteract its effects. For such schemes to be efficient and viable, however, the spread of AM-PM should be minimized in the analogue domain in the first place. Furthermore, this should ideally be achieved across the whole frequency range of operation, especially for power amplifiers that are required to operate over a very wide frequency range.